When did humans first come to the Americas? Scientists have debated this question for years. I wrote about the debate in my 2010 book Modern Humans, part of a four-volume series on human evolution.
Experts used to think that the Americas were peopled starting about 13,000 years ago. That date has been pushed back in recent decades. The latest evidence, summarized in this Scientific American article, suggests that the first humans may have reached the Americas as early as 18,000 years ago–and they may have come even earlier than that.
The question of when people came to the Americas, and from where, has been a hot topic in scientific circles for a long time. With archaeologists digging for more traces of early humans, and genetic sresearchers casting new light on the ways world populations have merged and split over time, the debate is sure to continue.